Dr. Dan Talks Agronomy

Turn Back the Covers

Dan Davidson
By  Daniel Davidson , DTN Contributing Agronomist
Some growers near Peoria, Illinois, seeded wet holes with cover crops this summer. It's one way to keep those areas from growing up in a tangle of weeds. (DTN photo by Pamela Smith)

Seeding fall covers requires innovation, planning and time. Mostly we seem to run out of the later when it comes to seeding covers. The snow is starting to fly here, so it may seem a funny time to write about cover crops. However, I've found it's never too early to plan what you'll do next year with this practice.

Earlier this fall, I wrote an article about the challenges of seeding cover crops, and it generated quite a few questions from readers. After posting that article, I spent a month seeding over 1,000 acres of cover crops in mostly bean stubble, and I had plenty of time to think about better seeding methods.

MY 2015 EXPERIENCES

I started out with a 20-foot drill that planted in 20-inch rows and seeding a mix of oats, barley, rye and peas. The drill is a John Deere soybean drill with soybean meters. I drilled at 7 to 8 miles per hour at 50 to 55 pounds per acre. Each fill allowed me to plant only 30 acres. Add the fact that I had to drive back to the farmstead to refill from a seed tender, and you can start to feel my frustration. I ended up seeding 80 acres a day in an eight-hour day. That may be acceptable for planting soybeans, but it was too slow for seeding covers in the fall.

I parked the drill after two weeks and moved to broadcasting seed with a fertilizer spreader and then incorporated it with a Kelly Harrow. I could broadcast seed in a 50-foot spread and cover 80 acres in an hour or so. I then pulled in with the 30-foot Kelly Harrow and ran at 7 to 8 mph, covering 80 acres in half the time as drilling. I also did not have to waste time tendering the broadcast spreader. What I would like to use is a Kelly Harrow with a seed box mounted on the frame with the ability to spread seed in front of the harrow and be able to cover 80 to 100 acres in half a day.

I started drilling on Sept. 18, and the last seed I broadcast was on Oct. 25. The covers drilled in September established quickly due to the warm fall and look great. I broadcast and incorporated the first seed on Oct. 9, and by Oct. 26, it was up and I could see a green hue over the field. The true testament is how the fields look on Nov. 1 (Can you see them?) and again on April 1 (Are they still there?).

SEEDING COVERS WITH STRIP TILLAGE

A landowner from Minnesota wrote and said: "Your article was timely since yesterday (for the first time) my new operator seeded cover crop into soybean stubble on his own farm going into corn for 2016. He used his 12-row strip-till machine set at 2 inches deep and a 5- to 6-inch wide strip. He was applying phosphorus and potassium along with oats and radish all mixed in the tank. We talked a lot about this over the summer, and he decided he just needs to get started with some type of cover crop practice. He's well aware the seed will not cover the entire surface, but there was no new equipment bought and seed cost was very low."

My comments: I do not consider row spacing a critical decision whether you drill in 7.5-inch or 10-inch rows, or plant in 15- or 20-inch rows or 30-inch rows or broadcast seed. What is important is establishing a cover crop to protect the soil and improving soil health. Mixing in some seed with the fertilizer and planting it in a strip is a novel approach to seeding covers.

SET EXPECTATIONS BEFORE AERIAL SEEDING

Aerial seeding covers can be a mixed bag -- it seems to work well in the Eastern Corn Belt, but I question its reliability in the Western Corn Belt when we lack the moisture and humidity at seeding.

A grower from Oklahoma said: "You are on the right trail looking for solutions. [I'm] having issues in southwest Oklahoma trying to establish cover behind cotton in the fall. I was very close to pulling the trigger on a broadcast seeder mounted on my JD 4730 sprayer to apply seed pre-defoliation [remove booms first). After your article and you not being impressed with aerial seeding, I think I will cancel that idea."

My comments: Aerial seeding seems like a good solution because someone else does it for you, but learn to temper your expectations. Maybe the challenge of establishment with aerial seeding lies not only with availability of rain, but also the condition of the soil at the surface. Perhaps if we learn how to optimize soil health, the success of aerial seeding will improve out in the Western Corn Belt.

SOIL CONDITIONS AT THE SURFACE ARE CRITICAL

A reader from Wisconsin wrote: "One observation here is the success (or not) of aerial seeding depends primarily upon the health of the soil surface upon which seeds are sown. Yes, it has to rain, but from what I've seen on hundreds of acres is that seeds broadcast onto brick-like soils (because they are not healthy to begin with) is a loser. Get the drill out. If you are true no-tilling with covers, you will have (in a shorter time than you might think) a soil surface receptive to successful broadcast seeding. Otherwise, any system that relies on even periodic tillage will probably not develop the soil surface properties needed for successful broadcast seeding."

My comments: The reader's comments ring true. It is much easier to aerial or ground broadcast seed on soybean stubble and get establishment than on cornstalks. This is partly due to less residue, but also the soil surface after a corn crop is harder than in bean stubble. However, I have learned that with a very healthy soil with high organic matter levels (3% or greater), a lot of microbial active carbon and microbial activity will be 'soft' regardless of the crop grown and provide a greater opportunity for covers to establish when broadcast.

Thanks to those who wrote. You've given me a lot to think about, and that's one of the pleasures of working with cover crops -- the practice keeps you thinking.

If you have a question, e-mail Dr. Daniel Davidson at askdrdan@dtn.com

(PS/AG)

Dan Davidson